On Tue, Jan 21, 2020 at 11:30 AM Andres Freund <andres@anarazel.de> wrote:
>
> Hi,
>
> On 2020-01-20 09:09:35 +0530, Amit Kapila wrote:
> > Pushed, after fixing these two comments.
>
> When attempting to vacuum a large table I just got:
>
> postgres=# vacuum FREEZE ;
> ERROR: invalid memory alloc request size 1073741828
>
> #0 palloc (size=1073741828) at /mnt/tools/src/postgresql/src/backend/utils/mmgr/mcxt.c:959
> #1 0x000056452cc45cac in lazy_space_alloc (vacrelstats=0x56452e5ab0e8, vacrelstats=0x56452e5ab0e8,
relblocks=24686152)
> at /mnt/tools/src/postgresql/src/backend/access/heap/vacuumlazy.c:2741
> #2 lazy_scan_heap (aggressive=true, nindexes=1, Irel=0x56452e5ab1c8, vacrelstats=<optimized out>,
params=0x7ffdf8c00290,onerel=<optimized out>)
> at /mnt/tools/src/postgresql/src/backend/access/heap/vacuumlazy.c:786
> #3 heap_vacuum_rel (onerel=<optimized out>, params=0x7ffdf8c00290, bstrategy=<optimized out>)
> at /mnt/tools/src/postgresql/src/backend/access/heap/vacuumlazy.c:472
> #4 0x000056452cd8b42c in table_relation_vacuum (bstrategy=<optimized out>, params=0x7ffdf8c00290,
rel=0x7fbcdff1e248)
> at /mnt/tools/src/postgresql/src/include/access/tableam.h:1450
> #5 vacuum_rel (relid=16454, relation=<optimized out>, params=params@entry=0x7ffdf8c00290) at
/mnt/tools/src/postgresql/src/backend/commands/vacuum.c:1882
>
> Looks to me that the calculation moved into compute_max_dead_tuples()
> continues to use use an allocation ceiling
> maxtuples = Min(maxtuples, MaxAllocSize / sizeof(ItemPointerData));
> but the actual allocation now is
>
> #define SizeOfLVDeadTuples(cnt) \
> add_size((offsetof(LVDeadTuples, itemptrs)), \
> mul_size(sizeof(ItemPointerData), cnt))
>
> i.e. the overhead of offsetof(LVDeadTuples, itemptrs) is not taken into
> account.
>
Right, I think we need to take into account in both the places in
compute_max_dead_tuples():
maxtuples = (vac_work_mem * 1024L) / sizeof(ItemPointerData);
..
maxtuples = Min(maxtuples, MaxAllocSize / sizeof(ItemPointerData));
--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com